1. Field of the Invention
The present invention relates generally to medical devices and, more particularly, to sensors used for sensing physiological parameters of a patient.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring many such physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. In fact, the “pulse” in pulse oximetry refers to the time varying amount of arterial blood in the tissue during each cardiac cycle.
Pulse oximeters typically utilize a non-invasive sensor that transmits light through a patient's tissue and that photoelectrically detects the absorption and/or scattering of the transmitted light in such tissue. One or more of the above physiological characteristics may then be calculated based upon the amount of light absorbed or scattered. More specifically, the light passed through the tissue is typically selected to be of one or more wavelengths that may be absorbed or scattered by the blood in an amount correlative to the amount of the blood constituent present in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of blood constituent in the tissue using various algorithms.
Accurate pulse oximetry measurements depend on the secure placement of a sensor on the desired measurement site on a patient's skin. Pulse oximetry sensors are typically either disposable bandage-type structures that attach the sensor components to the patient with adhesive materials, or reusable clip-type devices that affix the sensor components in place with tension provided by a spring. Regardless of the type of sensor used, the sensor should fit snugly enough that incidental patient motion will not dislodge the sensor, yet not so tight that normal blood flow is disrupted, which may interfere with pulse oximetry measurements. Furthermore, lack of a secure fit may allow ambient light to reach the photodetecting elements of the sensor, thus introducing error into the pulse oximetry measurements. Additionally, sensor movement may lead to motion artifacts, another potential source of measurement error.
Pulse oximetry sensors are used in emergency room and trauma center settings where the sensor may be exposed to liquids and/or bodily fluids. A patient's sweat or blood, for example, may interfere with the ability of adhesive bandages to adhere to the skin. Further, reusable sensors are subject to frequent repositioning, which may lead to weakening of the mechanical components of a clip-style sensor. Thus, an improved securing mechanism may be desirable.